Control mechanism for rock cutting equipment

ABSTRACT

This invention relates to the control of the speed of traverse of a rock cutting machine utilizing an operating head in the form of a rotor carrying swinging hammers. The control is effected by comparing the position of the hammer relative to the rotor at a predetermined time after impact with the position at which the hammer would have been if it had struck at its optimum position relative to the rotor. Any difference in the positions compared is then used to control the speed of traverse of the machine to bring about an elimination of this difference and thus ensure that the hammers strike in their optimum positions.

States Paten Taylor et a1.

CONTROL MECHANISM FOR ROCK CUTTING EQUIPMENT Inventors: Richard F. Taylor, Honeydew;

Christos Dimitriou, Johannesburg, both of Republic of South Africa Anglo-Transvaal Consolidated Investment Company Limited, Johannesburg Transvaal, Republic of South Africa Filed: July 25, 1972 Appl. No.: 275,051

Assignee:

Foreign Application Priority Data July 29, 1971 South Africa 71/5063 U.S. Cl ..299/1,173/1,173/4, 173/113, 299/81 Int. Cl. E2lc 29/00 Field of Search 299/1; 173/1, 4, 173/113 [56] References Cited UNITED STATES PATENTS 1,283,618 11/1918 App 299/1 2,218,528 10/1940 Endsley 173/113 X Primary Examiner-Ernest R. Purser Attorney-Richard K. Stevens et a1.

[57] ABSTRACT This invention relates to the control of the speed of traverse of a rock cutting machine utilizing an operating head in the form of a rotor carrying swinging hammers. The control is effected by comparing the position of the hammer relative to the rotor at a predetermined time after impact with the position at which the hammer would have been if it had struck at its optimum position relative to the rotor. Any difference in the positions compared is then used to control the speed of traverse of the machine to bring about an elimination of this difference and thus ensure that the hammers strike in their optimum positions.

9 Claims, 5 Drawing Figures THIS INVENTION relates to control mechanisms for rock cutting equipment and more particularly to the control of equipment using swinging hammers on a power driven rotor. Such equipment will usually consist of a motor and traversing gear similar to that used on long wall coal cutters. The cutting head will however be in the form of the rotor carrying swinging hammers and mounted on the end of the jib. The traversing gear will include means for varying its speed.

From experiments to date it appears important that the hammers of such rock cutting equipment should strike the rock when the tips are travelling parallel or nearly parallel to the line of the rock face, which direction is, of course, normally parallel to the direction of traverse of the rotor. In order to ensure that this occurs it is important that the rotor carrying the swing hammers should traverse across the rock at a speed which:

a. will ensure that there is sufficient rock for the hammers to hit, but

b. is not so fast that the hammers have too much work to do and thus strike behind the above-defined optimum striking position.

It is the object of the present invention to provide means for controlling the speed of traverse of the rock breaking equipment in order to obtain efficient operation of the rock breaking hammers.

According to this invention there is provided a a method of controlling the rate of traverseof rock cutting equipment including a support with a rotor carrying swinging hammers, which method comprises the generation of a signal ata predetermined angular position of a hammer relative to the rotor after an operational impact, applying the signal so generated to an indicating unit to determine the angular position of the rotor relative to the support at the moment of impact, comparing the position so determined with a predetermined relationship of the angular position of the rotor and utilising any difference from the predetermined relationship to vary the rate of traverse of the rotor across the rock face.

The invention also provides for the generated signal to be electrical or hydraulic.

The invention also provides means for controlling the traverse speed of rock cutting equipment including a rotor carrying swinging hammers and mounted on a support, said means comprising a sensor unit mounted on the rotor and adapted to generate a signal when a hammer is in a predetermined position relative to the rotor and after an operational impact, and an indicator unit adapted to receive the signal generated by the sensor and utilise this signal to determine the angular position of the rotor relative to the support at the moment of the operational impact and means for altering the traverse speed dependent on indications from the indicator unit.

Further features of the invention provide for a control unit associated with the indicator unit and able to vary the speed of traverse of the rotor.

Still further features of this invention provide for the sensor unit to be electrical, magnetic or mechanical members, for the traverse rate control to be automatic and for the rate of traverse to be adjusted to the requirements of the hammer orhammers on the rotor which meet the greatest operational resistance.

The invention also provides for the sensor unit to include one or more of the following members, namely, magnetic switches, proximity switches, hydraulic pressure switches or contact micro-switches.

Preferred embodiments of this invention will be described below by way of example only, reference being made to the accompanying drawings in which FIG. I is a cross-sectional side elevation of a rotor for a rock-cutting machine;

FIG. 2 is a diagrammatic side elevation of a rotor shown relative to the rock face and the body of the machine;

FIG. 3 is a circuit diagram illustrating one type of circuit which may be used;

FIG. 4 is a circuit diagram illustrating a second type of circuit; and

FIG. 5 is a cross-sectional side elevation of a rotor for a rock cutting machine, said rotor having alternate forms of controlling means.

As shown in FIGS. 1 and 2 the machine has a rotor with three hammers, two of said hammers (indicated by numeral 1) located in a swung-out position prior to an operational impact and the third hammer 2 in a swung back position after impact.

The rotor is designed to revolve in the direction of the arrow 3. In the position shown the rotor has revolved approximately 40 after the hammer 2 struck the rock face 4 at point 5. The impact took place when hammer 2 was in the position 6 indicated by dotted lines.

Thus, as shown, the hammer 2 has swung back and has struck the back stop or shock absorber 7 which has been compressed and has forced out a jet of water at 8.

The machine includes speed control mechanisms and three types of sensor units are indicated in FIG. 1. Any one or combination of these may be used in the control mechanism. These units are a. a reed switch 9 which will be switched on when the magnet at 10 approaches it and'thus will indicate when the hammer has swung back a certain distance;

b. a push type microswitch at 11 which will be switched on when the extended cap 12 of the back stop 7 strikes it; and

c. a pressure switch in place of the microswitch at 11 and connected to the passage for the water jet 8 will also be switched on when the water pressure rises due to the back stop being struck by the hammer.

It will be appreciated that there are many other ways of using standard commercial sensing devices in order to generate a signal when a hammer has swung back a predetermined distance due to having struck the rock.

If, due to the rock not breaking, the striking point of the hammer when striking the rock face at 5 has momentarily become stationary relative to the rock, it will swing back in the manner of a pendulum and operate whichever switching assembly is installed, after a delay which will be practically constant for a particular rotor speed and geometry of machine.

As shown in FIG. 1, this delay is equal to about 40 or 1/9 of a revolution of the rotor which is equivalent to a certain period of time.

Should the rock break easily the striking point of the hammer will only be slowed down relative to the rock and thus will swing back more slowly relative to the rotor and may only operate the switching mechanism, say 45 or of a revolution of the rotor after striking the rock.

In FIG. 2 the position of the rotor of FIG. 1 is shown relative to the rock face 4 and the main body of the machine 13.

In order to indicate the position of the blow of the hammer relative to the main body of the machine, it is necessary to relate the signal given by the switch 9 or 11 to the position of the rotor relative to the main body of the machine and to make an allowance for the time lag between the moment of impact and moment at which the signal is generated by the sensor unit. In this case, the lag is 40 of one revolution of the rotor. Two methods of achieving this will be described a. The signals from the switches 9 or 11 can be taken from the rotor through a commutator to an indicating panel on the main body of the machine. To do this a number of brushes would be connected to the commutator at close intervals. These brushes would be connected to lighting circuits which would only light up when the particular brush was connected to the particular segment of the commutator and the switch 9 or 11 was closed.

b. Instead of a commutator a slip ring may be used which would take out the signal from the rotor but would pass it through one or more of a number of circuits incorporating reed switches. These reed switches would be switched on by magnets on the rotor or rotor driving mechanism.

FIG. 2 illustrates the commutator with three segments 14. These are electrically connected to each other and to one end of the switches associated with the hammers 1 and 2, for example, reed switches 9. The commutator has three other segments which are insulated from the circuitry.

Resting on the slipring are seven brushes 15 which are mechanically attached to the body of the machine. These brushes are identified as a, b, c, d, e,fand g.

A slipring 16 with a single brush 17 completes the switching circuit into the rotor.

A simplified circuit diagram illustrating the type of circuit which may be used is shown in FIG. 3. The commutator and slipring are co-axial in the same position as indicated in FIG. 2.

The three switches 9 (1), 9 (l) and 9 (2) are the reed switches activated by the magnets on the hammers l, 1 and 2. It will be seen that switch 9 (2) is closed in consequence of hammer 2 having swung back after striking the rock at the optimum point (FIGS. 1 and 2).

Should all three switches be open, it will be seen that the battery 18 feeds current through resistances 19 to the lamps 20. The resistances will preferably be chosen so as to allow the filaments of the lamps 20 to be hot but not to shine brightly.

If one switch, say 9 (2), is closed and if the commutator is in the position shown in FIG. 3, then the subcircuits connected by brushes d, e,fand g will short circuit across the corresponding resistances 19d, e, fand g, and allow the corresponding lamps d, e,fand g to burn brightly. Should the hammer hit the rock at the point 5 (a), it will be seen that it will swing back earlier and the switch 9(2) will operate when the segment 14 of the commutator is in contact with more of the brushes 15 say with 15, b, c, d and e, lighting up the equivalent lamps 20b, 0, d and e. A fraction of a second later, while switch 9 (2) is still closed the segment 14 will have moved in such a manner that the sub-circuits b and c will have been broken and the sub-circuits f and g made. Shortly thereafter either the switch 9 (2) will open or the segment 14 will have broken all the circuits. In either case all the lights will go dimmer before being relighted by the next sequence of switching.

Conversely, if the hammer hits the rock at the point 5 (b) or if the rock at 5 breaks easily, without completely halting the tip of the hammer, the switch 9 (2) will close later and only, say, lamps 20fand g will light Whereas the lighting of the lamps has been described above with reference to one hammer 9 (2) only, it will be understood that the other hammers 9 (1) operate in the same manner to switch on the same lamps as hammer 9 (2). For a certain situation, the respective lamps will remain continuously lighted.

If each hammer in turn strikes at the same point 5 in the working face and the machine holding the rotor is stationary then the same lights will remain lit by a series of electric pulses generated in the above circuitry. However, should the rock not break and the hammers continue to strike at the same point 5 but the machine supporting the rotor be transversed in the direction of arrow 22 then this point 5 becomes in effect point 5 a and the lights 20 b, c, d and e will light up as described above. Similarly should the rock at point 5 break then the hammers will strike at point 5 b and only the lights, say 20 e,fand g will light up until the traversing of the machine brings the point 5 b in a relationship such as that of point 5 in the drawings.

It has been determined from tests that optimum results are normally obtained when the striking point is such that the line jointing that point to the centre 22 of the rotor is at right angles to the direction of traverse 21 of the machine depending on the condition and type of rock this optimum striking point may vary slightly from the point defined above. However, the traverse speed controls can be operated just as easily to give a striking point which forms an angle slightly greater or lesser than the above-mentioned right angle with 21 and 22. The simplest method of doing this is by altering the colour of the lights 20 as discussed below.

As the direction of traverse 21 of the machine is parallel to the newly formed face 23 this means that the optimum results will be obtained when the angle between the line extending from the centre 22 of the rotor and the point 5, and the line of the rock face 23 is a right angle. If the lamps 20a, b and c are tinted red, 20 d left clear and 20 e,fand g tinted green, a machine operator looking at the lamps would see the following i. Green lights if the hammers were striking in the region of point 5 (b). In this case he should increase the rate of traverse of the machine to ensure optimum breaking conditions.

ii. Green lights and the white light if the hammers were striking in the region of point 5. In this case he would maintain the existing rate of traverse of the machine.

iii. Green, white and red lights if the hammers were striking in the region of point 5a. In this case he would have to slow down or even stop the rate of traverse of the machine to allow the process of rock breaking to reach point 5 again.

A simple automatic control operated by the lamp circuits could be used to relieve the observer of the traverse speed control duties in which case the lights themselves would only be required as supplementary information for the machine operator.

FIG. 4 shows an alternative circuit using magnets 24 attached to a driving chain sprocket 25 for the rotor. These magnets operate reed switches 26 a, b, c, d, e, f and g.

It will be seen that an extra slipring 27 and brush 28 is required. i

The above simple circuit description relate only to one row of hammers in one rotor. They can be expanded to deal with a larger number of rows and numbers of hammers in each row and various modifications may be introduced. For example ll. Schmitt triggers or other relays can be incorporated which will allow the lamps to burn for a longer period on each cycle.

2. Sequencing cutouts (conveniently incorporated in the Schmitt trigger units) can be used to ensure that only the most important lamp lights up. For example, if circuits b, c, d and e were to be excited, circuit b would light up and cut out circuits 0, d and e. The single red light b would then indicate that the rate of traverse of the machine across the rock face is too fast.

3. The slipring l6 and brush 17 may be eliminated by connecting the points 29 to the body of the machine 13 and point 30 to the body of the rotor. In this case reliance is placed on electrical continuity of the bearings etc. of the rotor.

It is anticipated that more sophisticated control arrangements will be included in the development of the rock cutting equipment but where the assemblies above described are not considered desirable, for instance, because of the presence of methane, a further system is described which could be operated without electricity, although it also could be used with an electrical systern.

The system depicted in FIG. 5 involves the direct indication of the position of the water jet at 8 relative to the main body 13 of the machine. Because the position of jet 8 is constant relative to the pivot 30 of the hammer 2 and because the lag between the hammer striking a full blow against the rock and striking the shock absorber 7 is virtually constant when lag is measured as an angle of rotation of the rotor the system indicates the position of the point of impact of the hammer against the rock relative to the main body of the machine and in particular to the centre 22 of the rotor.

The system involves directing the jet of water at 8 at a series of pressure sensitive sensors 32 a, b, c, d, e, f and g mounted on the body 13 of the machine in such a position that the water jet strikes sensor 32d first, as a result of the hammer 2 hitting the rock at point 5. It will be seen that if the hammer strikes at 36 the first sensor to be hit might be 32a or b and if the hammer strikes at 37 that the first sensor to be hit might be 32f or g.

lt will be appreciated that the sensors can be designed to give pneumatic, hydraulic, electrical or simple mechanical signals or a combination of these and that they can be made to control the rate of traverse of the machine through a control unit either automatically or with manual assistance.

The invention also includes within its scope that the hammers shall strike the rock when they are travelling approximately parallel to the old and new rock faces as shown in FIGS. ll, 2 and 5.

It is further envisaged that practical benefit will be obtained from monitoring and controlling the power consumption and speed of the rotor together with the depth of cut, the striking position of the hammers and the rate of machine traverse.

Such benefits will become most apparent when machines involving more than one cutting rotor are used.

It will be apparent that it is not essential for the operation of all the hammers to be monitored for effective control of the traversing speed to be obtained. For instance, where a rotor consists of a plurality of rows of hammers with three hammers in each row and if only one hammer in each row has a sensor unit associated therewith, then the system will monitor every third impact. This is considered to be adequate for traverse speed control.

However, by including all the hammers in the system it will be possible to monitor the effective operation of the hammers to a certain degree. If, during operation, a rhythmic flickering of the lights described above is obtained, this could indicate that one of the striking points on one of the hammers was broken and causing the hammer to strike the rock slightly later than when in normal synchronism. This will enable repairs to be effected before undue damage is caused to the machine.

What we claim as new and desire to secure by letters Patent is:

1. A method of controlling the rate of traverse of rock cutting equipment including a support with a rotor carrying swinging hammers, which method comprises the generation of a signal at a predetermined angular position of a hammer relative to the rotor after an operational impact, applying the signal so generated to an indicating unit to determine the angular position of the rotor relative to the support at the moment of impact, comparing the position so determined with a predeter' mined relationship of the angular position of the rotor and utilising any difference from the predetermined relationship to vary the rate of traverse of the rotor across the rock face.

2. A method of controlling the rate of traverse of rock cutting equipment as claimed in claim 1 in which the generated signal is electrical.

3. A method of controlling the rate of traverse of rock cutting equipment as claimed in claim 1 in which the generated signal is hydraulic.

4. Means for controlling the traverse speed of rock cutting equipment including a rotor carrying swinging hammers and mounted on a support, said means comprising a sensor unit mounted on the rotor and adapted to generate a signal when a hammer is in a predetermined position relative to the rotor and after an operational impact, and an indicator unit adapted to receive the signal generated by the sensor and utilise this signal to determine the angular position of the rotor relative to the support at the moment of the operational impact and a control unit for altering the traverse speed dependent on indications received from the indicator unit.

5. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 4 in which the sensor unit is an electrical switching and signal generating assembly adapted to be activated by electrically magnetically or mechanically operated members.

6. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 in which the indicator unit includes a commutator with a set of an- 8. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 including a relay adapted to generate a signal in response to the signal received in the indicator unit but of longer duration than the signal received.

9. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 including a sequencing cutout circuit adapted to be fed by the signal received in the indicator unit. 

1. A method of controlling the rate of traverse of rock cutting equipment including a support with a rotor carrying swinging hammers, which method comprises the generation of a signal at a predetermined angular position of a hammer relative to the rotor after an operational impact, applying the signal so generated to an indicating unit to determine the angular position of the rotor relative to the support at the moment of impact, comparing the position so determined with a predetermined relationship of the angular position of the rotor and utilising any difference from the predetermined relationship to vary the rate of traverse of the rotor across the rock face.
 2. A method of controlling the rate of traverse of rock cutting equipment as claimed in claim 1 in which the generated signal is electrical.
 3. A method of controlling the rate of traverse of rock cutting equipment as claimed in claim 1 in which the generated signal is hydraulic.
 4. Means for controlling the traverse speed of rock cutting equipment including a rotor carrying swinging hammers and mounted on a support, said means comprising a sensor unit mounted on the rotor and adapted to generate a signal when a hammer is in a predetermined position relative to the rotor and after an operational impact, and an indicator unit adapted to receive the signal generated by the sensor and utilise this signal to determine the angular position of the rotor relative to the support at the moment of the operational impact and a control unit for altering the traverse speed dependent on indications received from the indicator unit.
 5. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 4 in which the sensor unit is an electrical switching and signal generating assembly adapted to be activated by electrically magnetically or mechanically operated members.
 6. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 in which the indicator unit includes a commutator with a set of angularly spaced brushes adapted to conduct a signal from the sensor unit.
 7. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 in which the indicator unit includes a slipring and brush assembly for the conduction of a signal from the sensor unit, a number of electrical circuits associated with the assembly and each circuit incorporating a reed switch and magnets on the rotor with the reed switches being adapted to be energized by the magnets.
 8. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 including a relay adapted to generate a signal in response to the signal received in the indicator unit but of longer duration than the signal received.
 9. Means for controlling the traverse speed of rock cutting equipment as claimed in claim 5 including a sequencing cutout circuit adapted to be fed by the signal received in the indicator unit. 